The invention relates to a breech system for a firearm, with a breech capable of being locked in its movement in the barrel block by means of at least one locking element, which is brought into contact against the rear end of the barrel by means of a breech spring, whereby the breech spring is supported at the rear section of the barrel by at least one connection element, subjected to tension.
A distinction is made between the following types of the breech system for automatic and semi-automatic pistols, rifles, machine pistols, and carbines:
The pure mass breech, i.e. the relatively small mass of the projectile round is opposed by a correspondingly high mass of the breech (the breech must not have moved any further before the round has left the barrel than the length of the cartridge case, or the delayed mass breech, i.e. in addition to the interplay of the masses, a rigid or semi-rigid breech is used, which restrains the movement of the breech until the round has left the barrel, and, with regard to the gas pressure, until pressure relief has been established in the barrel.
The first version is characterized by the corresponding simplicity and reliability, but because of the high loading stress involved can only be used for small projectile rounds, e.g. 9 mm Luger. For larger calibers, e.g. 45 Auto (0.45 inch Automatic Colt Pistol), a very powerful breech spring would be required, which would render manual loading or repeating almost impossible unless the spring travel were very long, which in turn leads to corresponding size and weight, as shown by the example of the MP38 machine pistol, caliber 9 mm Luger, of German design from the Second World War.
The second version requires corresponding additional structural and technical effort, whereby with long-barreled weapons the delay is usually achieved by means of tapping the gas pressure in the barrel. By means of one or more hole(s) in the barrel the gas pressure is diverted to a number of breech elements; once the round has left the barrel, the gas pressure drops off and the breech elements clear the breech (DtG 58, StG 77 and many others). In isolated cases handguns are also encountered which make use of this principle (Steyr GP). The main disadvantage lies in the gas holes themselves, since if they become blocked this can lead in the simplest situation to malfunction, and in the worst case to the user being injured.
The most widely encountered version in the case of handguns is the Browning System, where the barrel is prevented by a system of slots and grooves in its movement rearwards until the round has left the barrel. When the round has left the barrel, the force which holds the barrel in its position drops off (created by the fact that the round is actually somewhat larger than the diameter of the barrel), and the barrel moves to the rear by itself and tilts downwards. The disadvantage with this arrangement is the moving barrel, with which it cannot be guaranteed that it will be in exactly the same position again after each shot (in relation to the sight, which is secured to the retractor or slide). A further disadvantage is the relatively high mass of the moving parts (480 g for the Colt M1911), from which the user acquires the subjective feel of the recoil and which makes the rapid repetition of aimed shots one after another difficult or even technically impossible (cadence).
In AT 393 028 B a self-loading pistol is described which is provided with a rigid barrel even for larger calibers (45 Auto). Originally designed as a gas-pressure loader for assault weapons, the system was converted for self-loading pistols, whereby, among other features, torus segments are used as semi-rigid locking elements. These torus segments engage on the outside in corresponding torus nest mounts of the system part, and on their inside are prevented by a round control piston from releasing the locking mechanism too rapidly. This system is intended to function in accordance with the principle of the “Newtonian balance”, whereby the pulse resulting from the energy of the explosion, which is disseminated equally in all directions, impinges on the locked breech part, but this immediately passes its energy onto the control piston in the interior of the breech piece, which moves rapidly to the rear and so releases the torus segments. The proper function, or the malfunction equally, depends solely on the manufacturing tolerances interacting by chance in their totality in such a way that the torus segments are not fully locked but exhibit a slight degree of play, which must, however, not be sufficiently great as to damage the segments. A total of the smallest parts would therefore have to be capable of being produced in such a form that the total of the tolerances with double and triple passes is just great enough for the breech piece to begin to move, but small enough for the torus segments not to be over stressed, which, incurred due to the design, at one point in time are located at only one point inside and one point outside, and are subjected over a line to flexural and shear stress.
DE 31 09 730 discloses a weapon with a breech which can be locked in its movement in the barrel block by at least one locking element, which is pressed against the rear end of the barrel by a locking spring, via at least one connection element subjected to tension. The barrel itself is movable, however, so that, because of the play induced by manufacturing technology, it can never be ensured that the barrel, after the discharge, will be in exactly the same position as it was before. With a movable barrel, however, the locking spring must be located at a distance, which increases the space requirement and makes the weapon more unwieldy. In addition t to this, the opposing lines of force which are exerted by the gas pressure of the round in the barrel on the breech and the closure force of the locking spring, cause a disturbance in the weapon, which is likewise very detrimental to the precision of the shot.
The weapon which is described in DE 29 14 396 likewise has a breech which can be locked in its movement in the barrel block by means of at least one locking element, which is forced against the rear end of the barrel by a locking spring by means of at least one connecting element subjected to tension. The barrel itself is likewise again movable, with the disadvantages referred to heretofore of the play incurred by manufacturing technology, with impairment of shooting precision. Again, therefore, the lines of effect of the forces which are exerted by the gas pressure of the round in the barrel onto the breech and the closure force of the locking spring are opposed to one another, which is likewise detrimental to shooting precision. The weapon also does not exhibit any supporting bolt breech as a mechanical delay, but a pure rolling breech, while a type of support bolt alone serves to support the barrel to the front. This therefore forms only a limitation on the movement of the barrel in its initial position before the shot is discharged.